Exposure-timing device



Sept. 14 1926.

l ,599,507 R. ABRAHAMsoN EXPOSURE TIMING DEVICE Filed Jan. lf2. 1922 2 sheets-smet 1 i 4L la7 59 al-F L f 24g a? 26' 6 ZL :20 2 23 E" Z2 [nre/Mor Sept. 14 1926.

R. ABRAHAMSON EXPOSURE TIMING DEVICE 2 Sheets-Sheet Filed Jan.

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Patented Sept. 14, 1926.

UNITED STATES ROBERT ABRAHAMSON, OF GARDNER, MASSACHUSETTS.

EXPGSURE-TIMING DEVICE.

Application filed January 12, 1922.

This invention relates to a. device for automatically controlling the time of exposure in a machine for printing photographs or for making blue prints or other similar reproductions. j

t is the object of my invention to provide improved mechanism of this type by which an exposure of predetermined and definite length may be secured, together with 1o means by which the predetermined length or time of exposure may be varied as required. f

With this general object in view` an important feature of my invention relates to the provision of means by which the machine both closes and o ns the light circuit, thus absolutely de ning the time of exposure to the printing light. The machine also preferably restores the red or oange light, as the printing light is shut Other features ofmy invention relate to improved devices for adjusting the time of exposure and to certain arrangements and combinations of parts which will be hereinafter described and more particularly pointed out in the appended claims.`

A preferred form of my invention is shown in the drawing in which- Fig. 1 is a planview of my improved timing device;

Fig. 2 is a side elevation thereof;

Fig. 3 is a diagrammatic view indicating the light circuits and illustrating the method of operation;

Fig. 4 is a plan view of the mechanism with the casing removed;

i Fig. 5 is a side elevation of the mechanism;

Fig. 6 is a detail sectional elevation taken along the line 6-6 in Fig. 4, and

Fig. 7 is a transverse sectional elevation taken along the line 7--7 in Figs. 4 and 6.

Referring to the drawings, I have shown my improved timing device as provided with a casing 10 having a depressed p0rtion 11 and a longitudinally extending slot' 12. A scale 13 is mounted in the depressed portion 11 adjacent the slot 12 and may be graduated in minutes or desiredl ractionnl parts thereof.

The general arrangement and operation of my timing device is illustrated in diaammatic form in Fig. 3 in which is shown a battery 20, a white or printing light 21,

e rod or orange light 22, a. wire 23 connect- Serial No. 528,858.

ing the light 21 to a swinging contact 24, a wire 25 connecting the light 22 to a fixed contact 26, wires 27 connecting the battery or other source of electricity to the lights 21 and 22 and a common return wire 28 connecting the battery to a Sliding contact member 29. The member 29 is irictionally held in position by screws 30 and is provided with projections 31 and 32. A bar 33 is mounted to slide adjacent the member 29 and is provided with a projection 34 adapted to engage the projection 32 on the member 29. The bar 33 is provided with rack teeth 35 engaged by a gear 3G which is rotated at constant speed by a motor (not shown) when the device is in operation. A

plate 37 is adjustably secured to the sliding f bar 33 and is provided at one end with a. projection 3S adapted to engage the projection 31 and at the opposite end with a non-conducting portion 39 positioned to engage the swinging contact 24.

The operation of the mechanism is as follows: The plate 37 is adjusted on the bar 33 for the desired length or time of eX- posure, which time depends upon the relative positions of the projections 34 and 38, assuming a constant motor speed. The bar 33 is then ushed to the left to the position shown in ig. 3, swinging the Contact 24 back against a stop pin 40 and moving the Contact member 29 away from the Contact 26 but not moving the member-29 fer enough toy engage the contact 24. Both light cir'- cuits are then open.

The bar 33 is then released and themotor Y mechanism acts through the gear 3G to move the bar 33 at a regulated rate' toward the' This movement first releases the right. swinging Contact 24, permitting the same to engage the member 29 and complete the circuit through the white or printing light 2l. This circuit remains closed until the bar 33 has moved far enough to cause the projection 34 to engage the projection 32. The member 29 is then moved to the right. separating it .from the swinging contact 24 which is limited in its movement by a second stop pin 4 1. The printing circuit is thus broken but continued movement of the bar 33 and member 29 to the right will cause engagement with the Xed contact 26, closing the circuit through the dim light 22, which may be used to illuminate the interior of the printing machine while fresh printing paper is being inserted.

Having described the diagrammatic representation and operation ot my improved machine. l will now describe one embodiment oi" my invention as shown in Figs. el to T. The mechanism is mounted on an inner `trame comprising upper and lower brass plates and 5l spaced apart by posts and secured by screws 53. The sliding contact member l is preferably mounted on a wood block and is secured thereto b v screws 5G extending through short slots 5T (F ig. Ll) in the member 5l. @ne end ot 'the member 5l is upturned to provide lejection 5S. and a stud .39 is secured to member 5l at an intermediate point. thereof.

A lixed Contact is secured on one end ot the wood block 55 and a swinging contact Gl is pivoted at (52 on said block. these contacts being connected by the wires and to the light circuits as indicated in Fig. f3. EL spring G5 is conneted to move the ccntact 6l trom the stop pin (36 toward the p pin GT whenever such movement is permitted.

Guide-ways 'TO (F igs. Ll and T) are secured to the under side ot the plate 50 and a raclr bar Tl is mounted to slide in said guide-ways. A gear 72 engages the rack bar and is driven by a spring motor mechanism indicated generally by a reference numeral 73 in Fig. 5. This motor mechanism includes a governor or speed controiler Tl geared to the motor and causing the same to move the rack bar at a predetermined unitorm rate of travel.

The rack bar is provided with a slot 75 extending substantially the whole length thereof. plate 76 is mounted beneath the rack bar il and is slidably secured in the slot T5 by a guiding block 7T (Fig. 6) extending upward through the slot and a short upper plate T8 covering the slot at its upper side.

An index T9 is secured to the plate 7S and co-operates with the graduated scale 13 shown in Fig. l. The plate TS is loosely mounted on pins S0 (Fig. 6) secured in the block 'TT and the plates TG and 78 may be forced together to securely grip the rack bar T5 by means of a clamping screw Sl extending freely through the plate 78 and threaded in the plate 7G and block 7T. By loosening this clamping screw the plate T6 may be adjusted relative to the rack bar 'T5 as desired.

Re. section S2 (Fig. el) ot insulating material is secured to one end ot the plate 7G in position to engage the swinging contact 6l. and a stud (Fig. is tixed in the plate in position to engage the stud 59 on the contact member 5l.

The common return wire Q8 may be secured to any convenient part of the metal ot the mechanism, as by a screw 8l (Fig.

4). The electrical connection is completed through the post to the plate 5l and thencethrough a screw engaging the under side ot the sliding contact member The screw is made ot such length as to engage the member 5l and bend it htly upwardly, thus insuring a goed Contact between the parts and also lnfovidine' the neressary friction to prevent dis-` Yznfement thereof. The operation ot the de ice has already been fully described in detail.

The time ot exposure may be varied by adjusting the plate 'TG by means ot the clamping screw Si. This 'aries the distance between the projection S3 on the plate 7G and the end ot the rack bar T5 which engages the upturned portion 5S et the contact member 54, The screw Sl also serves as a handle 'tor moving the )arts to the lett. preliminary to a printing exposure. This movement winds thel spring motor au amount equal to the rotation oit the motor in returning the rack bar to its normal position.

lllhen the end of the rack bar engages the part 58 and torces it against the fixed contact 60 -further movement ot the racl( bar is prevented and the motor stops. The motor is thus wound sufliciently for each operation thereof by the action ot settingr the machine Jfor operation and it requires no other attention. It is a matter ot great practical importance that the printing circuit is not established until atter the handle 8l has been released and the motor has started to move the rack bar along its guide-ways. lVith this arrangement, the printing period cannot be increased by holdingr the handle 8l in its lett hand position.. as both the making and the breaking ot the circuit is determined by the movement oit the rack bar and the time interval is determined solely by the speed of the motor and the adinet-ment of the plate T6 relative to the rack bar.

Having thus described my invention. it

Sii

will be evident that changes and modificai tions can be made therein by those skilled in the art within the spirit and scope ot my invention as set forth in the claims. and I do not wish to be otherwise limited to the details herein disclosed but what I claim l., An exposure timing device having, in combination. a tixed contact. a movable contact. a contact member movably mounted between said contacts. said member being trictionally positioned. means to cause said member and contacts to be successively engaged, and an actuating device `t'or said means. said means comprising a sliding bar formed in two pieces relatively adjustable longitudinally.

2. An exposure timing device having, in combination, a fixed contact, a movable contact, a contact member movably mounted between said contacts, said member being frictionally positioned, means to cause said member and contacts to be successively engaged, and an actuating device for said means, said means comprising a sliding bar formed in two pieces relatively adjustable longitudinally and the portion engaging the movable contact being a non-conductor of electricity.

3. An exposuretiming device having, 1n combination, a contact member, a support on which said member is movably mounted and frictionally held, a movable contact engaged by said member at one endof its path of travel, timing means engaging said contact member and said movable contact as the def vice is set for operation, and an actuator to ment, a iixed contact device at one end of the path of travel of said bar, a movable contact device at the other end of its travel, a timing bar adjustable as to length, said timing bar being positioned to engage said movable contact at one end of its path of travel and to engage said contact member at both ends of its travel, and a speed regulated motor to move said timing bar.

5. An exposure timing device having, in combination, a sliding contact member with separated projections thereon, a movable contact, a slotted bar adapted to engage one projection on said contact member, a plate adjustably secured to said slotted bar and adapted to engage the second projection on said contact member, and means to move said bar and plate to cause successive engagement of said projections and resultant limited movement of said contact member in opposite directions, whereby a circuit through said movable contact and Contact member is made and broken.

In testimony whereof I have hereunto aiixed my signature.

ROBERT ABRAHAMSON. 

